How to define a string?

Strings can be written in single quotes or double quotes.

Example:

PHP

<?php
$str1 = 'Hello';
$str2 = "World";
echo $str1 . " " . $str2;  // Outputs: Hello World
?>

What is string concatenation?

Concatenation joins two or more strings using the . (dot) operator.

Example:

PHP

<?php
$first = "PHP";
$second = "Rocks";
echo $first . " " . $second; // Outputs: PHP Rocks
?>

Common String Functions

Function	Description	Example
`strlen()`	Returns length of a string	`strlen("PHP")` → 3
`strtoupper()`	Converts string to uppercase	`"php"` → `"PHP"`
`strtolower()`	Converts string to lowercase	`"PHP"` → `"php"`
`ucfirst()`	Capitalizes first character	`"php"` → `"Php"`
`strrev()`	Reverses a string	`"PHP"` → `"PHP"`
`strpos()`	Finds position of substring	`"Hello", "e"` → 1
`str_replace()`	Replaces text in a string	`"World" → "PHP"`
`trim()`	Removes whitespace from both ends	`" PHP "` → `"PHP"`

Example of string functions

PHP

<?php
$str = " Hello PHP World ";
echo strlen($str);              // Length
echo strtoupper($str);          // Uppercase
echo strtolower($str);          // Lowercase
echo trim($str);                // Remove spaces
echo str_replace("PHP", "Java", $str); // Replace PHP with Java
?>

Escape characters in strings

Use backslash \ to escape characters like quotes inside a string.

PHP

<?php
echo "She said: \"I love PHP!\"";
?>

: HEREDOC and NOWDOC

Used for writing long strings with multiple lines.

HEREDOC Example:

PHP

<?php
$text = <<<EOD
This is a long paragraph
spanning multiple lines in PHP.
EOD;

echo $text;
?>

NOWDOC Example:

PHP

<?php
$text = <<<'EOD'
This will not parse variables like $text
EOD;

echo $text;
?>